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Combine two data frames by rows (rbind) when they have different sets of columns
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An alternative with data.table:
library(data.table)
df1 = data.frame(a = c(1:5), b = c(6:10))
df2 = data.frame(a = c(11:15), b = c(16:20), c = LETTERS[1:5])
rbindlist(list(df1, df2), fill = TRUE)
rbind will also work in data.table as long as the...
Update a table using JOIN in SQL Server?
I want to update a column in a table making a join on other table e.g.:
11 Answers
11
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On duplicate key ignore? [duplicate]
...).
Instead, since in your example tag is the unique key, use:
INSERT INTO table_tags (tag) VALUES ('tag_a'),('tab_b'),('tag_c') ON DUPLICATE KEY UPDATE tag=tag;
on duplicate key produces:
Query OK, 0 rows affected (0.07 sec)
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Rails migrations: Undo default setting for a column
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Rails 5+
def change
change_column_default( :table_name, :column_name, from: nil, to: false )
end
Rails 3 and Rails 4
def up
change_column_default( :table_name, :column_name, nil )
end
def down
change_column_default( :table_name, :column_name, false )
end
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SQL Server 2008: how do I grant privileges to a username?
I need to be able to establish an ODBC connection through SQL Server authentication.
3 Answers
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Keeping it simple and how to do multiple CTE in a query
I have this simple T-SQL query, it emits a bunch of columns from a table and also joins information from other related tables.
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How to create a new database after initally installing oracle database 11g Express Edition?
...O myschema;
Now you can connect via Oracle SQL Developer and create your tables.
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How to Publish Web with msbuild?
...Version parameter depend on your version of Visual Studio. Wikipedia has a table of Visual Studio releases and their versions.
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How do you return the column names of a table?
How would I return the column names of a table using SQL Server 2008? i.e. a table contains these columns- id, name, address, country and I want to return these as data.
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When/Why to use Cascading in SQL Server?
...eal key rather than a surrogate key (identity/autoincrement column) across tables.
The canonical example for Cascade Update is when you have a mutable foreign key, like a username that can be changed.
You should not use Cascade Update with keys that are Identity/autoincrement columns.
Cascade Updat...